Appartus for generating a heated oxygen enriched gas stream

ABSTRACT

The present invention relates to appartus for generating a heated oxygen enriched gas stream for use as combustion and reducing gas in a blast furnace wherein a stream of fuel gas is intimately mixed with a stream of combustion air, the resultant fuel gas-combustion air mixture is combusted so that a stream of hot combustion gases is produced under super atmospheric pressure and excess oxygen is combined with the hot combustion gases.

United States Patent Ebeling et a1. July 1, 1975 1 1 APPARTUS FOR GENERATING A HEATED 2,931,720 4/1960 De Vaney 266/29 OXYGEN 2.939.278 6/1960 FOX 1 1 1 e t 1 v. 431/19 3,265,113 8/1966 Thurley et al. 1 431/238 Inventors: Harold g; Russell H Smith. 3,386,475 6/1968 Horton et al1 1 11 431/153 both of Oklahoma City, Okla. $394,265 7/1968 Hendricksonm 60/3929 3,649,155 3/1972 Sharan .1 431/19 173] Asslgneel Black sm'us 3,778,047 12/1973 Stevens 1 1 v v .1 266/29 Houston, T919 3,779,694 12/1973 Zagorofl' 431/158 [22] Film: June I 1973 3,779.695 12 1973 Chamberlain 431 351 1 11 ppl- NO-I 3661083 Primary Examiner-Carroll B. Dority, Jr.

Related US. Application Data Division of Ser. No. 299083, Oct. 19, 1972.

References Cited UNITED STATES PATENTS 10/1935 Theunissen 431/352 12/1959 Nicita 1. .1

3/1960 Fraser .1 431/158 51.45 7' FOP/(.6465

Attorney, Agent, or Firm-C. Clark Dougherty, Jr.

[57] ABSTRACT The present invention relates to appartus for generating a heated oxygen enriched gas stream for use as combustion and reducing gas in a blast furnace wherein a stream of fuel gas is intimately mixed with a stream of combustion air, the resultant fuel gascombustion air mixture is combusted so that a stream of hot combustion gases is produced under super atmospheric pressure and excess oxygen is combined with the hot combustion gases.

2 Claims, 2 Drawing Figures APPARTUS FOR GENERATING A HEATED OXYGEN ENRICHED GAS STREAM This is a division, of application Ser. No. 299,083, filed Oct. 19, I972.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to apparatus for generating a heated oxygen enriched gas stream, and more particularly, but not by way of limitation, to apparatus for combusting a stream of fuel gas with air and oxygen so that a stream of heated combustion gases containing a desired concentration of oxygen for use in a blast furnace or the like is produced.

2. Description of the Prior Art Blast furnaces have been utilized for many years in the steel industry. That is, molten iron is obtained from iron ore by the reduction of the ore at high temperatures in blast furnaces. In operation of a blast furnace, combustion is forced by injecting a stream of air preheated to a temperature of approximately 2000F through the charge of ore, fuel and fluxing materials contained within the furnace. Heretofore, the stream of heated air has been generated in elaborate air heating apparatus. Typically, such apparatus includes one or more large refractory lined towers. The refractory is first heated by combustion of fuel and air within a tower and then a stream of air is forced through the tower so that it is heated to approximately 2000F prior to entering the blast furnace. Such heretofore used blast furnace air heating apparatus are expensive to install, difficult to operate and require expensive periodic maintenance.

SUMMARY OF THE INVENTION The present invention relates to apparatus for generating a heated oxygen enriched gas stream for use in blast furnaces or the like wherein the steps of intimately mixing a stream of fuel gas with a stream of combustion air, combusting the resultant fuel gascombustion air mixture so that a stream of hot combustion gases is produced under super-atmospheric pressure and then combining a stream of oxygen with the stream of hot combustion gases are carried out.

It is, therefore, a general object of the present invention to provide apparatus for generating a heated oxygen enriched gas stream.

A further object of the present invention is the provision of apparatus for generating a heated oxygen enriched gas stream which may be utilized for providing blast gas to blast furnaces for bringing about the reduction of iron ore.

Yet a further object of the present invention is the provision of apparatus for generating a heated oxygen enriched gas stream which is inexpensive and simple to install and operate and which requires very little maintenance.

Another object of the present invention is the provision of apparatus for generating a heated oxygen enriched gas stream wherein the gas stream may be generated on an intermittend or continuous basis without the necessity of preheating refractory or other similar steps.

Other and further objects, features and advantages of the invention will be readily apparent from a reading of the detailed description of preferred embodiments of the invention which follows when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic illustration of a conventional blast furnace and apparatus of the present invention for producing a heated oxygen enriched gas stream.

FIG. 2 is a diagrammatic illustration of an alternate form of apparatus of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Broadly described, the apparatus of the present invention for generating a stream of heated oxygen enriched gases brings about the intimate mixing of a stream of fuel gas with a stream of combustion air. The resulting combustion air-fuel gas mixture is combusted to convert the mixture to a stream of inert combustion gases under super-atmospheric pressure, and a stream of oxygen is combined with the combustion gases so that a heated oxygen enriched gas stream results.

Referring now to the drawings, and particularly to FIG. 1, apparatus of the invention is illustrated diagrammatically and generally designated by the numeral 10. A conventional blast furnace I2 is illustrated connected to the apparatus 10 by a conduit 14. The apparatus l0 basically comprises a high intensity combustion burner 16 having a fuel gas inlet connection 18 and a combustion air inlet connection 20. The burner apparatus 16 may take a variety of forms, but preferably is a high intensity combustion burner. High intensity combustion burners are characterized in that complete combustion takes place within the combustion chamber of the burner and no flame is emitted therefrom. Such burners include a mixing area for bringing about intimate mixing of a stream of fuel gas and a stream of combustion air introduced to the burner followed by a combustion chamber wherein the air-fuel mixture is combusted. The term high intensity combustion burner" is used herein to mean any gas burner appara tus having the capability of intimately mixing fuel gas with combustion air and bringing about the complete combustion of the air-fuel mixture thereby generating a stream of hot inert combustion gases without the discharge of flame from a burner. A particularly suitable such high intensity combustion burner for use in accordance with the present invention is described and claimed in US. Pat. No. 3,265,l 13 issued to .l. Thurley, et al. on Aug. 19, l966.

The high intensity combustion burner apparatus 16 includes a flanged combustion gas outlet connection 22. A conduit 24 is attached to the fuel gas inlet connection l8 and to a source of fuel gas. A conduit 26 is connected to the combustion air inlet connection 20 of the burner 16 and to a combustion air blower 28. The blower 28 may be any conventional blower or compressor capable of producing a stream of combustion air under super-atmospheric pressure.

Attached to the outlet connection 22 of the burner 16 is a mixing chamber 30. The chamber 30 may take a variety of forms, but preferably is cylindrical in shape and includes an inlet connection 32 attached thereto. The inlet connection 32 preferably connects to the mixing chamber 30 tangentially so that centrifugal action is imparted to a stream of oxygen introduced therethrough and intimate mixing of the oxygen with combustion gases passing through the mixing chamber 30 is achieved. The outlet 34 of the mixing chamber 30 is connected by an appropriate fitting 36 to the conduit 14. A conduit 38 is connected to the inlet connection 32 of the mixing chamber 30 and to a source of oxygen.

A flow control valve 40 is disposed in the conduit 24 and a conventional flow controller 42 is provided oper ably connected to the valve 40. The controller 42 receives a signal from a flow sensing device 44 disposed in the conduit 14 representative of the flow of oxygen enriched combustion gases passing through the conduit 14 and controls the flow of fuel gas to the burner 16 at a preset proportional rate. A second flow sensing device 46 is disposed in the fuel gas conduit 24 downstream of the control valve 40 operably connected to a second flow controller 48. The controller 48 is in turn operably connected to a flow control valve 50 disposed in the conduit 26. The controller 48 senses the flow of fuel gas passing to the burner 16 via the conduit 50 and controls the flow rate of combustion air to the burner via the conduit 26 at a preset proportional rate. A third flow controller 49 is provided operably connected to a flow control valve 52 disposed in the conduit 38. The controller 49 receives the signal representative of the flow of oxygen enriched combustion gases transmitted by the flow sensing device 44 and controls the flow of oxygen to the mixing chamber 30 at a proportional rate.

OPERATION OF THE APPARATUS In operation of the apparatus 10, fuel gas is conducted to the burner 16 by way of the conduit 24. The fuel gas utilized may be natural gas, coke oven gas or other available combustible fuel such as a mixture of coke oven gas and other steel mill waste gas streams. The flow controller 42 is set to control the flow of fuel gas to the burner 16 at a rate such that oxygen enriched combustion gases are generated by the apparatus 10 at the desired rate. A stream of combustion air produced by the blower 28 flows via the conduit 26 into the burner 16 and is intimately mixed with the stream of fuel gas within the burner 16. The flow controller 48 is set to control the flow of combustion air to the burner 16 at a preset rate proportional to the rate of fuel gas flowing to the burner 16. That is, the stream of combustion air is controlled at a rate such that a substantially stoichiometric fuel-air mixture results within the burner 16. The fuel-air mixture is combusted within the burner 16 thereby generating a stream of hot inert combustion gases. As will be understood by those skilled in the art, the streams of fuel gas and combustion air are introduced to the burner 16 under superatmospheric pressure so that the hot inert combustion gases generated are also under super-atmospheric pressure. The hot combustion gases flow from the burner 16 through the mixing chamber 30 wherein a stream of oxygen is intimately mixed with the combustion gases. The resulting heated oxygen enriched gas stream flows into the conduit 14 from where it flows to the blast furnace 12.

The flow controller 48 is set to control the stream of oxygen flowing into the mixing chamber 30 of the apparatus 10 at a rate proportional to the flow of heated oxygen enriched gases produced so that the gases contain the desired concentration of oxygen. The heated oxygen enriched combustion gases generated by the apparatus flow under super-atmospheric pressure through the conduit 14 and into the blast furnace 12.

Referring now to FIG '2, an alternate form of apparatus for carrying out the nethod of the present invention is illustrated and generally designated by the numeral 60. The apparatus 60 is similar to the apparatus 10 except a mixing chamber is not provided and instead of adding the stream of oxygen directly to the combustion gases. the stream of oxygen is added to the combustion air. The combustion air-oxygen mixture is mixed with the stream of fuel and then the mixture is combusted to generate a heated stream of combustion gases containing a desired concentration of excess oxygen.

The apparatus 60 includes a high intensity combustion burner 62 having a fuel gas inlet connection 64 and a combustion air inlet connection 66. A conduit 68 is connected to the fuel inlet connection 64 of the burner 62 and to a source of fuel gas. A combustion air blower 70 is provided connected to the combustion air inlet 66 of the burner 62 by a conduit 72. A conduit 74 is connected to a source of oxygen is connected to the conduit 72. A transition fitting 76 is provided connected to the combustion gas outlet of the burner 62, and a conduit 78 for conducting heated oxygen enriched combustion gases to a point of use is connected to the fitting 76. I

A flow sensing device 80 is disposed in the conduit 78 operably connected to a conventional flow controller 82. The flow controller 82 is operably connected to a control valve 84 disposed in the conduit 68. A flow sensing device 86 is disposed in the conduit 68 operably connected to a flow controller 88. The flow controller 88 is operably connected to a flow control valve 90 disposed in the conduit 72. A flow control valve 92 is disposed in the conduit 74 operably connected to a flow controller 94 which also receives the signal transmitted by the flow sensing device 80 disposed in the conduit 78.

OPERATION OF THE APPARATUS 60 In operation of the apparatus 60, a stream of fuel gas is conducted by the conduit 68 to the burner 62.The flow controller 82 controls the rate of fuel gas passing into the burner 62 at a level such that heated oxygen enriched combustion gases are generated by the apparatus 60 at a preset rate. A stream of combustion air produced by the combustion air blower 70 is conducted by the conduit 72 to the burner 62. The flow controller 88 controls the rate of the combustion air stream at a preset level proportional to the rate of the fuel gas flowing into the burner 62. That is, as described above with respect to the apparatus 10, the flow controller 88 is set so that a substantially stoichiometric mixture of fuel and combustion air is produced within the burner 62. In addition, a stream of oxygen is injected into the stream of combustion air via conduit 74 connected to conduit 72. The rate of the oxygen stream injected into the stream of combustion air is controlled by the controller 94 at a preset level which varies in proportion to the quantity of heated oxygen enriched combustion gases produced by the apparatus 60. That is, the controller 94 is set so that excess oxygen is contained in the combustion gases a desired concentration. The fuel-combustion air-oxygen mixture passing into the burner 62 is combusted therein and the resultant combustion gases containing excess oxygen flow into the conduit 78 as described above.

While presently preferred embodiments of the invention have been described for the purpose of disclosure, numerous changes in the details of construction and arrangement of parts can be made by those skilled in the art. For example, a variety of instruments, controls and arrangements thereof can be used for controlling the rates of the various fuel, air and oxygen streams introduced to the burner apparatus in lieu of the specific controls and arrangements described. These changes and various arrangements of parts are encompassed within the spirit of this invention as defined by the appended claims.

What is claimed is:

l. Apparatus for generating a heated oxygen enriched gas stream under superatmospheric pressure for use in blast furnaces and the like which comprises:

a high intensity combustion burner having a fuel gas inlet, a combustion air inlet, a chamber wherein fuel gas and combustion air are mixed and the mixture is combusted to produce combustion gases essentially free of flame and an outlet for discharging said combustion gases;

a mixing chamber having an inlet for receiving combustion gases, an inlet for receiving a stream of oxygen and an oxygen enriched combustion gas outlet, the combustion gases inlet of said mixing chamher being connected to said combustion gases outlet of said high intensity combustion burner so that all of the combustion gases produced by said high intensity burner are caused to flow into said mixing chamber;

a conduit connected to a source of fuel gas and to said burner fuel gas inlet;

a combustion air blower for generating a stream of combustion air under superatmospheric pressure connected to the combustion air inlet of said burner;

means attached to said combustion air blower for controlling the rate of combustion air introduced to said combustion burner in response to the flow of fuel gas supplied to said fuel gas inlet so that a substantially stoichiometric combustion air-fuel gas mixture results;

a conduit connected to a source of oxygen and to said mixing chamber oxygen inlet; and

means disposed in said conduit connected to a source of oxygen and responsive to the flow of gases leaving said mixing chamber for controlling the rate of oxygen introduced to said mixing chamber so that the combustion gases produced by said apparatus contain a desired concentration of oxygen.

2. The apparatus of claim 1 which is further characterized to include means disposed in said conduit connected to a source of fuel gas for controlling the rate of fuel gas introduced to said burner in proportion to the rate of the stream of heated oxygen enriched gases produced by said apparatus. 

1. Apparatus for generating a heated oxygen enriched gas stream under superatmospheric pressure for use in blast furnaces and the like which comprises: a high intensity combustion burner having a fuel gas inlet, a combustion air inlet, a chamber wherein fuel gas and combustion air are mixed and the mixture is combusted to produce combustion gases essentially free of flame and an outlet for discharging said combustion gases; a mixing chamber having an inlet for receiving combustion gases, an inlet for receiving a stream of oxygen and an oxygen enriched combustion gas outlet, the combustion gases inlet of said mixing chamber being connected to said combustion gases outlet of said high intensity combustIon burner so that all of the combustion gases produced by said high intensity burner are caused to flow into said mixing chamber; a conduit connected to a source of fuel gas and to said burner fuel gas inlet; a combustion air blower for generating a stream of combustion air under superatmospheric pressure connected to the combustion air inlet of said burner; means attached to said combustion air blower for controlling the rate of combustion air introduced to said combustion burner in response to the flow of fuel gas supplied to said fuel gas inlet so that a substantially stoichiometric combustion airfuel gas mixture results; a conduit connected to a source of oxygen and to said mixing chamber oxygen inlet; and means disposed in said conduit connected to a source of oxygen and responsive to the flow of gases leaving said mixing chamber for controlling the rate of oxygen introduced to said mixing chamber so that the combustion gases produced by said apparatus contain a desired concentration of oxygen.
 2. The apparatus of claim 1 which is further characterized to include means disposed in said conduit connected to a source of fuel gas for controlling the rate of fuel gas introduced to said burner in proportion to the rate of the stream of heated oxygen enriched gases produced by said apparatus. 